Thermoplastic molding compositions containing a mixture of polycarbonate and a polyester copolymer derived from cyclohexane dimethanol and phthalic acid have been disclosed in U.S. Pat. No. 4,786,692. Characterized by their low heat distortion temperatures, high tensile and flexural strength, the compositions are said to be compatible with impact modifiers and flame retardants. The addition of phosphite and phosphate stabilizers is noted at column 11, line 64. Also included in the art is U.S. Pat. No. 5,254,610 which disclosed adding a combination of aliphatic and aromatic phosphite compounds to a blend of polyester with polycarbonate. The resulting composition is said to be advantageous in terms of unexpected thermal stability and reduction of the spray during injection molding. The phosphite of the present invention is known to impart thermal stability to polycarbonate compositions.